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| -rw-r--r-- | Documentation/userspace-api/media/v4l/dev-overlay.rst | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/Documentation/userspace-api/media/v4l/dev-overlay.rst b/Documentation/userspace-api/media/v4l/dev-overlay.rst index 07cc92564c16..4f4b23b95b9b 100644 --- a/Documentation/userspace-api/media/v4l/dev-overlay.rst +++ b/Documentation/userspace-api/media/v4l/dev-overlay.rst @@ -37,6 +37,10 @@ capturing and overlay. Optionally these drivers may also permit capturing and overlay with a single file descriptor for compatibility with V4L and earlier versions of V4L2. [#f1]_ +A common application of two file descriptors is the X11 +:ref:`Xv/V4L <xvideo>` interface driver and a V4L2 application. +While the X server controls video overlay, the application can take +advantage of memory mapping and DMA. Querying Capabilities ===================== @@ -289,11 +293,6 @@ To start or stop the frame buffer overlay applications call the :ref:`VIDIOC_OVERLAY` ioctl. .. [#f1] - A common application of two file descriptors is the XFree86 - :ref:`Xv/V4L <xvideo>` interface driver and a V4L2 application. - While the X server controls video overlay, the application can take - advantage of memory mapping and DMA. - In the opinion of the designers of this API, no driver writer taking the efforts to support simultaneous capturing and overlay will restrict this ability by requiring a single file descriptor, as in |